Pause the game, and enter one of the following codes. If you entered the code correctly, you will hear a sound. Press Start to resume the game with the code(s) activated. Note: Some codes may only be enabled once per game. Also, codes that have multiple tiers (for example, credits) only take effect when activated in order (lowest to highest).

Successfully complete the game on any difficulty to unlock Ten Power Nodes, 50,000 credits, Level 6 Military suit schematic, Impossible difficulty, and the back story log entries.

Wear Military suit in Impossible mode

Successfully complete the game in New Game Plus mode with the Military suit bought and equipped, and save the game immediately before the final Boss. Once the game ends and the credits begin, skip them, and do not save the game when prompted. Instead, immediately start a new game on the Impossible difficulty to start with the Military suit.

Hidden message

Take the first letter of each chapter and arrange them in order to spell out the sentence "Nicole is dead."

Secret message key

In Chapter 1, just after you repair the claw for the tram, hit your objective finder. Follow the blue line into the hallway where you need to go. Stop as soon as you enter the hallway, and look up at the catwalk above your head; ignore the alien for now. Walk until you find the first corridor on the right. Walk in there to see writing in an alien language all over. Look down to see a message in English that reads "Don't listen to their lies, read what they're really saying." Keep reading to find a key that shows the alien language, and below that English letters from A to Z and 1 through 0. Although not everything will be legible, you should be able to decipher enough to understand what is written.

Finding the Peng Treasure

You must be on the flight deck on Chapter 11. When in the ship port after your ship has left, look between the walkways. You should see a statue shaped like an Oscar. Pick it up with kinesis, and you will get the Peng Treasure and "There's Always Peng!" trophy. It can also be sold for 30,000 credits. -From: PureNasher

When you are out of ammo, but have a bench and several Power Nodes, you can refill the ammo in a weapon to its new maximum by upgrading to a Capacity Node in that weapon.

Easy credits

Sell your Plasma Cutter at the store. It is worth a lot of credits, and a new one is completely free.

Purchase the Contact Gun as soon as possible. Ammunition for it will start appearing around the ship. Sell all of the unneeded ammo for it for 1,000 credits per unit.

In Chapter 2, when you enter the Zero G Therapy area, there is a hole on the right side of the room along with debris blocking the hallway to other side where you can see the planet. Once you go through the room on the left and get to the other side, back up to the debris. You can see something flashing outside in the direction of the planet. It is 10,000 credits.

Defeating the Hunter

The Hunter is a regenerating Necromorph that cannot be killed. The first time you encounter him it is difficult, and you just have to run. It is best to shoot off his legs because he does not regenerate them immediately. He is much slower without legs. Then, freeze him, and he will be taken away. When you face him again in a later chapter, use the same strategy, then fry him with the rocket engines, and collect the Power Node he drops.

Defeating the Leviathan

First, take out the tentacles. When the center opens, aim for the orange ball. Take the explosive canisters or the Lathan pod, and launch them in the center.

Defeating the final Boss

Do not be intimidated by its size. Though massive, it is easy to kill. The following was done on the Medium difficulty. When the battle begins, notice you are "caged in" by the Boss' tentacles. Notice the yellow "blooms" around the Boss' mouth. Shooting each one will get you closer to killing it. However, after shooting a few of them, the Boss will grab you and hold you in the air. During this time, it may appear you are helpless. Aim whatever weapon you are using at the time and shoot the yellow blooms. After a few shots, you will be dropped. The Boss will then begin slamming its tentacles at you more frequently. They are very easy to avoid. Strafe left to right constantly. They will never hit you. The Boss will roar, shoot a few exploding cells at you, or will drop enemy pods upon you. This part is also easy, considering it is usually only two small Necromorphs. After you destroy the blooms, you will notice a "caged" area underneath the beast. Under this rib cage lies its many hearts. Use the same strategy used for the tentacles. After a few times, the Boss will open up again. Unload on the Boss to kill it.

Trophies

Successfully complete one of the following tasks to get a trophy:

Dead on Arrival (Bronze): Complete Chapter 1 on any setting.

Lab Rat (Bronze): Complete Chapter 2 on any setting.

All Systems Go (Bronze): Complete Chapter 3 on any setting.

Cannon Fodder (Bronze): Complete Chapter 4 on any setting.

True Believer (Bronze): Complete Chapter 5 on any setting.

Greenhouse Effect (Bronze): Complete Chapter 6 on any setting.

S.O.S. (Bronze): Complete Chapter 7 on any setting.

Strange Transmissions (Bronze): Complete Chapter 8 on any setting.

Wreckage (Bronze): Complete Chapter 9 on any setting.

Keeper of the Faith (Bronze): Complete Chapter 10 on any setting.

Betrayed (Bronze): Complete Chapter 11 on any setting.

Exodus (Bronze): Complete Chapter 12 on any setting.

Pack Rat (Bronze): Store 25 items in Safe.

Story Teller (Bronze): Collect Half of all Logs.

Z-Baller (Bronze): Complete Level 6 in Zero-G Basketball.

Merchant (Bronze): Collect 5 schematics.

Armstrong (Bronze): TK shoot 50 objects.

Marksman (Bronze): Dismember 5 Limbs.

Surgeon (Bronze): Dismember 250 Limbs.

Freeze (Bronze): Use Statis on 50 Enemies.

Crackshot (Bronze): Achieve a perfect score in the Shooting Gallery.

Air Alert (Bronze): Zero G jump over 100 times.

Brawler (Bronze): Kill at least 50 enemies with a melee attack.

Ragdoll Check (Bronze): Force an enemy into a gravity panel.

Big Spender (Bronze): Spend 500,000 credits at the store.

Full Contact (Bronze): Kill 20 enemies with the Contact Beam.

A Cut Above (Bronze): Kill 20 enemies with the Ripper.

Tool Time (Bronze): Kill 20 enemies with the Plasma Cutter.

Pusher (Bronze): Kill 20 enemies with the Force Gun.

Live with the Hot Ones (Bronze): Kill 20 enemies with the Flamethrower.

Autofire (Bronze): Kill 20 enemies with the Pulse Rifle.

Eviscerator (Bronze): Kill 20 enemies with the Line Gun.

There's Always Peng (Bronze): Find the Peng Treasure.

Survivor (Silver): Beat the game on any difficulty setting.

Legend Teller (Silver): Collect all Logs.

Full Arsenal (Silver): Own every Weapon in the game.

Butcher (Silver): Dismember 500 Limbs.

Epic Tier 3 Engineer (Gold): Complete the game on the hardest difficulty setting.